The present invention relates to brake cleaner compositions useful for removing oil and particulate contamination from braking system components of vehicles, for example, automobiles.
In order to maintain proper functioning and performance of braking components (e.g., drums, rotors, calipers) on vehicles such as automobiles it is often necessary to clean the braking components (e.g., when replacing or inspecting brake pads or shoes) in order to remove any accumulated contaminants such as oil and brake pad or brake shoe dust.
One method by which brake components may be cleaned is to direct a pressurized stream of air at the contaminated surfaces of the brake components to forcibly dislodge contaminants. Such a technique is disadvantageous in that the particulate contamination, once dislodged, becomes airborne and may pose a health risk, if inhaled. Also, such a method will effectively remove oily deposits from brake components.
A second method involves the use of steam to clean braking components. This method is disadvantageous in that the steam may accelerate corrosion of metal brake system components.
The most commonly used method of cleaning brake components involves the use of spray-applied, solvent-based brake cleaner compositions. Using this method, the brake cleaner composition is sprayed (e.g., using an aerosol can) onto the contaminated brake components where it functions to loosen, dissolve and/or wash away accumulated oil and particulate contamination. Solvent-based brake cleaners typically comprise volatile organic compounds (VOCs) such as toluene, xylene, hexane, heptane, methyl alcohol, and may also include one or more chlorinated hydrocarbons. Due to the environmental awareness occurring today, laws and regulations have been enacted and will be enacted to limit the VIC level in many materials, in particular solvent-based cleaners such as brake cleaners. In California, for example, the California Air Resources Board (CARB) has recently imposed a 45% VIC limit on brake cleaner compositions sold and/or used within the state of California. Chlorinated hydrocarbons such as methylene chloride and perchloroethylene have also been subject to regulation due to their status as hazardous air pollutants (HAP) and suspect carcinogens.
In order to be accepted solvent-based brake cleaners must provide a desirable balance of several important properties. For example, the brake cleaners must quickly and efficiently dissolve oil and must wet out particulate contamination such as brake dust. Further, the brake cleaners must dry at an acceptable rate under a variety of environmental conditions. That is, the brake cleaner must dry at a rate that is slow enough to allow the liquid flow of brake cleaner over the contaminated brake component to carry the dissolved and/or loosened brake contamination off of the contaminated component(s). If the brake cleaner dries too quickly, dissolved and/or loosened brake contamination will simply be redeposited onto the surface to be cleaned as the brake cleaner dries. If the cleaner dries too slowly, on the other hand, it may interfere with proper performance of the brake components. Generally, a brake cleaner should dry within a period of about 15 to 45 seconds after it has been applied. Another important property of a brake cleaner is its solvent strength or its ability to dissolve and/or loosen brake contamination. If the solvent compatibility with the contaminants is too low, the brake cleaner will not be effective in removing contamination from the braking component. The solvent may also undesirably attack brake system components (e.g., rubber hoses, wheel cylinder boots, and the like) and other vehicle components (e.g., body side moldings, paint, plastics, wheels and tires) during use. Yet another important property of a brake cleaner is odor. Although inhalation of brake cleaners is to be avoided, it is inevitable that during use of a brake cleaner some of the brake cleaner will be inhaled by a worker who is either applying the brake cleaner or working in the vicinity of where the brake cleaner is being applied. In view of this, it is desirable to provide a brake cleaner composition that has an acceptable and low odor.
In view of the foregoing, an effective spray-applied brake cleaner composition having low VIC content (i.e., less than 45%), low toxicity, acceptable odor, acceptable dry time, and excellent cleaning performance is desired.
The present invention provides a brake cleaner composition comprising (1) about 5% to about 30% by weight methyl acetate; (2) about 25% to about 50% of a hydrocarbon according to formula CnH2n+x, where n is 5 to 8 and x is 0 or 2; and (3) about 25% to about 55% by weight acetone.
In a preferred embodiment, the hydrocarbon is selected from the group consisting of n-pentane, isopentane, n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, methyl cyclohexane, cyclohexane, and mixtures thereof.
In another preferred embodiment of the brake cleaner composition the methyl acetate is present in an amount ranging from about 5% to about 20% by weight of the composition, more preferably 5% to 10% by weight.
In another preferred embodiment of the brake cleaner composition the hydrocarbon is present in amount ranging from about 30% to about 45% by weight of the composition.
In another preferred embodiment, the acetone is present in an amount ranging from about 45% to about 50% by weight of the composition.
In another preferred embodiment, the brake cleaner composition further includes water in an amount ranging from about 1% to 15% by weight.
In another preferred embodiment the brake cleaner composition is provided in a pressure-resistant container under the pressure of an aerosol propellant. Preferred aerosol propellants include, for example, propane, isobutane, normal butane, nitrogen, carbon dioxide, and mixtures thereof.
The brake cleaner composition preferably includes a fragrance additive such as d-limonene. Fragrance additive d-limonene is typically present in an amount ranging from about 0.05% to about 3% by weight of the composition.
Preferred embodiments of the brake cleaner composition have less than about 50% by weight volatile organic compounds, more preferably less than about 45% by weight volatile organic compounds.
Brake cleaner composition of the present invention comprise at least the following three components:
(1) about 5 to about 30% by weight of methyl acetate;
(2) about 25% to about 50% by weight of a hydrocarbon according to the formula:
CnH2n+x,
where n is 5 to 8;
x is 0 or 2; and
(3) about 25% to about 55% by weight acetone.
Brake cleaner compositions of the present invention comprise from about 5% to about 30% by weight methyl acetate (CH3CO2CH3). Presently, methyl acetate is not classified as a volatile organic compound making its use in brake cleaner compositions of the present invention desirable. Methyl acetate combined with a hydrocarbon of the formula above provides a composition having a high degree of solvency to oil and grease and further provides brake dust wetting capability. In addition, methyl acetate has a desirable level of volatility allowing for the formulation of brake cleaner compositions having a desirable drying rate. Methyl acetate also acts to reduce and/or dilute the objectionable odor of acetone, preferably to an acceptable level. In preferred embodiments, the brake cleaner composition of the present invention comprises from about 5% to about 10% by weight methyl acetate.
Brake cleaner compositions of the present invention further comprises at least one hydrocarbon solvent fitting within the general formula (1):
CnH2n+x,xe2x80x83xe2x80x83(1)
wherein: n ranges from 5 to 8 (more preferably ranging from 6 to 7); and x is 0 or 2 (preferably 2).
Hydrocarbons included within this formula include, for example, n-pentane (n-C5H12), isopentane (i-C5H12), n-hexane (n-C6H14), isohexane (i-C6H14), n-heptane (n-C7H16), isoheptane (i-C7H16), n-octane (n-C8H18), and isooctane (i-C8H18), methyl cyclohexane (C7H14), cyclohexane (C6H12). Optionally, brake cleaner compositions of the present invention may include more than one hydrocarbon according to general formula (1). The preferred hydrocarbon of formula (1) for use in brake cleaner compositions of the present invention is n-heptane due to its balance of solvent strength, drying rate (i.e., volatility), toxicity and odor. As hydrocarbons of general formula (1) are classified as volatile organic compounds, it is preferred to limit the total amount of these hydrocarbons in order to provide a low VIC brake cleaner composition. Brake cleaner compositions of the present invention include at least one hydrocarbon according to general formula (1) in an amount ranging from about 25% to about 75% by weight of the composition. More preferably, brake cleaner compositions of the present invention include at least one hydrocarbon according to general formula (1) in an amount ranging from about 25% to about 50% by weight, and most preferably ranging from about 30% to about 45% by weight. Heptane suitable for use in brake cleaner compositions of the present invention is commercially available under the trade designation xe2x80x9cEXXSOL HEPTANE FLUIDxe2x80x9d from Exxon Chemical Company.
Brake cleaner compositions of the present invention also include acetone (CH3COCH3), an organic solvent that is not presently classified as a volatile organic compound. Acetone is present in brake cleaner compositions of the present invention in an amount ranging from about 25% to about 55% by weight, more preferably ranging from about 25% to about 55% by weight, most preferably about 45% to about 50% by weight. Suitable acetone may be obtained under the trade designation xe2x80x9cACETONE 99.5% GRADExe2x80x9d from Shell Chemical Company.
Brake cleaner compositions of the present invention may optionally include water. Water may be intentionally added to the formulation as a low cost diluent. If added, water is typically included in an amount ranging from about 2% to about 15% by weight of the brake cleaner composition. Water may also be present in as an impurity in one or more of the components of the brake cleaner composition. For example, industrial grade methyl acetate typically includes about 0.05% to about 5% by weight water. If added, it is generally preferred to use deionized or distilled water to reduce the quantity of dissolved mineral in the brake cleaner composition. If water is present in the brake cleaner composition, it may be desirable to add a corrosion inhibitor to reduce or prevent corrosion of aerosol cans.
Brake cleaner compositions of the present invention may optionally include a fragrance additive. One preferred fragrance additive is d-limonene that provides a citrus odor. When included in a brake cleaner composition of the present invention a fragrance additive such as d-limonene is typically added in an amount ranging from about 0.05% to about 3% by weight of the total composition. Suitable d-limonene fragrance additive is commercially available under the trade designation xe2x80x9cD-LIMONENE, TECHNICAL GRADExe2x80x9d from Florida Chemical Company.
Brake cleaner compositions of the present invention are preferably supplied in an aerosol spray can for convenient application. When provided in an aerosol spray can, a propellant is included with the brake cleaner formulation. Suitable propellants include, for example, nitrogen, carbon dioxide, propane, isobutane, normal butane, and mixtures thereof. Typically, liquid aerosol propellants such as propane, butane, and isobutane are added to the brake cleaner composition in an amount ranging from about 5% to about 15% by weight of the composition. When the aerosol propellant is itself classified as a volatile organic compound (e.g., propane, butane, isobutane) the quantity of hydrocarbon solvent of formula (1) is preferably reduced in order to provide a composition having less than 45% by weight total volatile organic compounds. When gases such as nitrogen and carbon dioxide are used as the propellant, the gas propellant is typically present in an amount ranging up to about 2% by weight. Propane suitable as an aerosol propellant is commercially available under the trade designation xe2x80x9cA-110xe2x80x9d from Technical Propellants, Inc.
Brake cleaner compositions of the present invention may be prepared by mixing the desired components, for example, using a low shear type mixer. The order of addition of the various components has not been shown to affect the resulting brake cleaner composition. Typically and preferably, explosion-proof manufacturing facilities and equipment must be used in mixing and packaging of the brake cleaner compositions.
Brake cleaner compositions of the present invention are preferably provided in and aerosol spray can to facilitate application of the composition to difficult-to-reach surfaces such as are typically present in brake system assemblies. In typical use, the brake cleaner compositions of the present invention are preferably spray-applied to the surface(s) to be cleaned until such surface(s) are thoroughly wetted with the brake cleaner composition. After initial wetting, it may be desirable to further spray the brake cleaner composition onto the surface(s) to be cleaned in order to loosen and/or flush away contaminants. Multiple applications of the brake cleaner composition to the surface to be cleaned may be desired in some circumstances. Any run-off of brake cleaner composition and contamination must be collected and disposed of using proper disposal techniques.